over again. we know it can tremendously upsetting to have an event that's horrific and random over which they have no control, especially for kids. >> pelley: you've been talking to a number of the emergency room physicians. what were they seeing as they came through the door? >> they saw anything from shrapnel wounds, they didn't know whether it was shrapnel from a bomb but pieces of metal blown into people's legs, a leg that was blown off, glass injuries, eardrums that were burst and more serious injuries that led to somebody going up to the operating room and being operated on for a terrible injury to the leg. >> pelley: and we know that several children were also wounded in this. jon, thank you very much. we do not know who did this, whether it was terrorism inspired by a foreign source or domestically. it's very early in the investigation. but bob orr in our washington newsroom has been talking to his sources all afternoon and, bob, what are you hearing at this point? >> well, scott, the field is still wide open as to who might have done this and for what possible reason. the bombs don't appear to be very large.